Multi-cylinder pump



July 24, 1962 H. s. HAHN MULTI-CYLINDER PUMP 4 Sheets-Sheet 1 Filed May 4, 1960 ll IIIII Elllll I IHJIII' u II" INVENTOR HERBERT s. HAHN BY A7 ATTORNEY July 24, 1962 H. s. HAHN 3,04

MULTI-CYLINDER PUMP Filed May 4, 1960 4 Sheets-Sheet 2 mL. im

1?! E El INVENTOR HERBERT S. HAHN BYW i ATTORNEY July 24, 1962 H. s. HAHN 3,045,604

MULTI-CYLINDER PUMP Filed May 4, 1960 4 Sheets-Sheet 3 INVENTOR HERBERT S. HAHN 8 BY W /MM VZL/ ATTORNEY July 24, 1962 H. s. HAHN 3,04

MULTI-CYLINDER PUMP Filed May 4, 1960 4 SheetsSheet 4 INVENTOR HERBERT S. HAHN ATTORNEY United States Patent 3,045,604 MULTI-CYLINDER PUMP Herbert S. Hahn, Lansing, Mich., assignor to FMC Corporation, a corporation of Delaware Filed May 4, 1960, Ser. No. 26,883 4 Claims. (Cl. 103-173) This invention relates to pumps and more particularly to reciprocating pumps which have rotatable drive members.

An object of the invention is to provide an improved multi-cylinder pump.

Another object of the invention is to provide a multicylinder pump that requires no parts of close dimensional accuracy.

Another object of the invention is to eliminate force couples in the application of extension and retraction force to the reciprocable piston rods of a multi-cylinder pump.

Another object is to provide an improved mechanism for transmitting the force exerted by a rotatable drive member to the reciprocable pistons of a pump.

Another object is to provide improved piston rod retracting levers for use in a multi-cylinder pump.

Another object is to provide a multi-cylinder pump that is easily and inexpensively maintained.

Another object is to provide an improved apparatus for coupling a drive shaft to a driven shaft.

These and other objects and advantages of the invention will be apparent from the description and accompanying drawings wherein:

FIGURE 1 is an end elevation of the multi-cylinder pump of the invention.

FIGURE 2. is a side elevation of the pump.

FIGURE 3 is a partial longitudinal section of the pump on an enlarged scale, the section being taken on section line 3-3 of FIGURE 1.

FIGURE 4 is a transverse section through the body of the pump, the section being taken on section line 44 of FIGURE 3.

FIGURE 5 is an isometric of the ends of the four piston rods of the pump and the associated retracting levers.

FIGURE 6 is an exploded isometric on an enlarged scale of coupling apparatus for the drive shaft of the pump.

FIGURE 7 is an enlarged transverse section through the coupling apparatus, the section being taken on section line 77 of FIGURE 3.

FIGURE 8 is also an enlarged transverse section through the coupling apparatus, the section being taken on section line 8--8 of FIGURE 3.

The pump 10 (FIGS. 1 and 2) of the invention comprises a housing 12 and an end plate 13 bolted to the housing 12 by means of several bolts and nuts 14. The pump includes four pumping cylinders 16 (FIG. 1) which extend leftward from the housing 12 and are in communication with an adjacent valve housing 18. The valve housing contains a fluid inlet port 20 (FIG. 3) and a fluid discharge port 22, and each cylinder 16 receives fluid from the inlet port and forces it out the outlet port through a series of fluid-operated valves (not shown) which are located in the valve housing 18. These valves are more fully disclosed in the application of C. I. Grifiith et al., Serial No. 757,587, for Pump Valve Structure which is assigned to the assignee of the application.

The end plate 13 (FIG. 3) contains an inner and an outer ball bearing assembly, 24 and 26, respectively, which assemblies support for rotation a longitudinally bored shaft 28 of a pump driving member 30. The shaft 28 is coupled by means of a coupling collar 32 to a splined drive shaft 34. Rotation of the drive shaft 34 causes the rotation of the driving member 30 and the operation of the pump.

The driving member 30 (FIG. 3) includes a flat circular plate 36 having a flat annular surface 38 which is inclined and lies in a plane disposed at an angle of approximately to the longitudinal axis of the driving member shaft 28. The smoothly finished flat annular surface 38 is slidably engaged by fiat surfaces 39 on each of four circular shoes 40. Each shoe 40 contains a semispherical depression 42 for receiving the spherical end 44 of an associated piston rod 46. Each piston rod 46 extends into a respective one of the four pumping cylinders 16 and, since the pumping cylinders are structurally alike, only one will be described in detail.

Each piston rod 46 extends from the shoe 40' through a bushing 47 and through a resilient annular seal 48 into a cylindrical chamber 50 in the housing 12. Each chamber 50 is counterbored at 52 (FIG. 3) to receive one end of a longitudinally drilled cylinder 54. The other end of the metal or ceramic cylinder 54 is received in a counterbore 56 in the valve housing 18. The piston rod 46 extends into the cylinder 54 and terminates in an integral projection 58 of reduced diameter. A piston 59, in the form of a circular cup 60 of resilient material and two flat washers 62 and 63, is retained on the end of the piston rod projection 58 by means of a cap screw 66. The cylinders 54, the pump housing 12, and the valve housing 18 are urged tightly together in leak-proof relation ship by studs 68 which engage the housing 12 and extend through the valve housing 18 to receive nuts 70.

Rotation of the driving member 30 causes the inclined surface 38 on the member to rotate in sliding engagement with surfaces 39 of each of the four shoes 40. The four shoes and associated piston rods 46 are projected leftward as seen in FIG. 3 in succession by the camming action of the high portion of the driving member 30. The four piston rods are also retracted, each in its turn, as the member 30 is rotated, the retraction, however, is under the control of a pair of rockable retracting levers 72 and 73 (FIGS. 3-5) which are disposed in the housing 12 adjacent the driving member 30.

The spherical ends 44 of the piston rods 46 are each laterally drilled to receive pins 76, 77, 78 and 79, (FIG. 5) respectively. The pins 76 and 78 in the diametrically opposed piston rods 46 (FIG. 4) are engaged by a pair of fingers 80 and 82, on the respective ends of the rockable retracting lever 72. Similarly, the pins 77 and 79 on the diametrically opposed piston rods 46 are engaged by a pair of fingers 83 and 85, on the respective ends of the lever 73. Each finger of each of the four described pairs of fingers includes a flat surface 88 which is engaged with the shank of the adjacent pin (FIGS. 3 and 5) near the end thereof, and each finger includes a shoulder 89 which is disposed in a plane which lies at approximately 90 to the plane of the surface 88.

A spring loaded plunger (FIG. 3) engages the rockable retracting lever 72 for continuously urging the four surfaces 88 of the lever 72 into engagement with the shanks of pins 76 and 78. A spring-loaded tubular plunger 102 engages the rockable lever 73 for continually urging the four surfaces 88 of that lever into engagement with the pins 77 and 79.

The tubular plunger 102 is slidingly received in a bore 104 in the fixed pump housing 12, the bore 104 being axially aligned with the longitudinal axis of the shaft 28 of the driving member 30. An annular shoulder 106 in the bottom of the bore 104 supports a disc 108. A compression spring 110 is located between the disc 108 and the end of the plunger 102 and urges the plunger 102 out of the bore 104. The plunger 102 includes a semispherical end 112 which engages a socket 114 formed at the center of the rockable retracting lever 73. The spring 110 urges the flat surfaces 88 of the fingers on lever 73 into tight engagement with the piston rod pins 77 and 79 (FIG. 5) and thus urges the associated piston rods into the sockets 42 in the respective shoes 40 and urges the surfaces 39 of the associated shoes 40 into fiat engagement with the inclined surface 38 of the driving member 30.

The tubular plunger 102 receives the plunger 100 in sliding engagement. The plunger 100 includes a semispherical end 116 that is urged into engagement with a socket 118 in the retracting lever 72 by a compression spring 120 placed between the other end of the plunger 100 and the disc 108. Spring 120, through the lever fingers and engaged pins 76 and 78 urges the associated piston rods 46 and shoes 40 into continuous engagement with the inclined surface 38 of the driving member 30. Spring 110 and spring 120 have approximately the same rate, and the forces applied thereby are approximately equal.

The plunger 100 has an axial projection 100a on its inner end and this plunger can be moved into the bore 104, compressing spring 110, to the extent permitted by the abutment of the projection 100a and a raised platform 108a in the center of the disc 108. The tubular plunger 102 includes an annular flange 102a on its outer circumference which is adapted to abut the housing at 10411 and thus limit the inward movement of the plunger 102 against the urging of spring 110. The projection 100a and the flange 102a thus prevent the over-compression of the associated spring which might occur if a valve becomes damaged or clogged and this construction ensures the positive retension of the piston rods within a predetermined distance of the plate surface 38 to thus prevent the shoes 40 from falling off.

It will be apparent from FIG. 3 that, as the driving member 30 rotates, the high portion of the surface 38 engages the shoes 40 in succession and projects the associated piston rod leftward. During this movement, the pin on the piston rod engages the associated retracting lever and rocks this lever about its associated plunger. The pin 76 on the upper piston rod 46 shown in FIG. 3, for example, engages the fingers 80 on the end of the retracting lever 72 and rocks the lever 72 counterclockwise (as seen in FIG. 3) about the end 116 of the associated plunger 100, into the illustrated position. Counterclockwise movement of lever 72 causes the pair of fingers 82 at the other end thereof, which engage pin 78, to positively retract the associated piston rod 46 while maintaining the engagement of the end of the piston rod- 46 in the shoe depression 42 and maintaining the engagement of the shoe surface 39 and the surface 38. The spring 120 can be selected to provide a slight amount of resiliency in the maintenance of the last mentioned engagements, the spring 120 should, however, be sufficiently stiff to maintain at least a light contact between the engaged surfaces during the operation of the pump. The spring 110 can be selected to provide the same slight resilience between the levers 73 and its associated piston rods 46. The springs 110 and 120 automatically compensate for any wear or other dimensional inaccuracies which may occur between the several engaged surfaces, and the several parts of the pump therefore need not be originally manufactured within close dimension tolerances. The range of permissible tolerances can, in fact, be quite large, permitting mass production of pumps at minimum cost.

It will be noted that the fiat surfaces 88 on the fingers at each end of a retracting lever continuously maintain a line contact with the associated piston pin, and that the retracting force is applied simultaneously to both ends of the pin and therefore simultaneously to both sides of the piston rod. There are no couples set up by a onesided application of the retraction force. No onesided force causes the bushings 47 and seals 48 to wear unevenly or causes the piston rods to bind; on the contrary, the retraction force which is applied by the pair of fingers on opposite sides of the piston rod is substantially equivalent to application of the force along the longitudinal axis of the piston rod. With this structure there is no tendency for any moving parts to wear unevenly or to bind.

The driving member 30 acts through the shoe 40 that is universally pivotable on the semi-spherical end 44 of the associated piston rod to apply the projecting force to the associated piston rod along the longitudinal axis thereof. This application of the piston rod projecting force is similar to the above-described retraction force because there are no force couples set up and therefore there is no uneven Wear and no tendency of any of the parts to bind even after extended periods of operation.

The above-described line contact between the piston rod pins and the associated surfaces 88 on the two fingers on the associated end of the retracting lever is continually maintained during pump operation and thus it will be clear that as the retracting lever 72 rocks it remains in one plane. The lever never twists or rolls within that one plane, such as might occur if there were only point contact at each of the piston rods. The retracting lever 73 likewise rocks in only one plane during the pump operation and the line contact at its ends is continuously maintained by the spring 110, preventing any twisting or erratic movement of the lever. This structure assures a long trouble-free pump life because the retraction force is applied along a line of contact and not a point of contact.

The sockets 114 and 118 do not swivel on the ends 112 and 116 of the spring-loaded plungers 102 and 100, respectively, and there is therefore no tendency for these parts to wear unevenly or to bind.

When it becomes necessary to replace one of the circular resilient cups 60 of the piston 59in a pumping cylinder 16 (FIG. 3) replacement can be done easily and quickly by removing the nuts 70 and removing the valve housing 18. With the valve housing removed, the cap screws 66 are exposed and these can then be unscrewed and the cup 60 quickly replaced. The piston rod 46 is prevented from rotating during the loosening and tightening of the cap screw 66 by the pin on the other end thereof which engages the shoulders 89 on the retracting lever fingers. With the piston rods prevented from rotating by this structure, there is obviously no need to disassemble the end plate 13 from the valve body 12 when a cup 60 is being replaced.

The assembled pump housing 12 and end plate 13 (FIG. 3) enclose a chamber which is to be partially filled with oil. The oil is introduced through a plugged fill opening 131 (FIGS. 1 and 2) and can be drained through a plugged drain opening 132 (FIG. 3). The oil lubricates all moving parts including the surfaces 38 and 39 and the bearing assemblies 24 and 26. A seal assembly 134 surrounds the driving member shaft 28 adjacent the bearing assembly 26 and prevents leakage of oil out the end plate 13.

The driving member shaft 28 (FIG. 3) is coupled to the splined drive shaft 34 by an improved coupling collar 32 (FIGS. 6-8). The outside diameter of the splined shaft 34 is slightly smaller than the inside diameter of the longitudinally drilled shaft 28, so that the splined drive shaft 34 can be readily inserted into the shaft 28. The inner cylindrical surface 140 of the shaft 28 is drilled at three equiangular locations in the longitudinal direction to provide three semi-cylindrical grooves 142 in the surface 140. Three cylindrical keys 144, each of which has a fiat surface 146 thereon and a tapped hole 148 adjacent one end thereof, are inserted in the semi-cylindrical grooves 142 until each of the tapped holes 148 is aligned with a respective radially drilled and countersunk hole 150 in the shaft 28. Flat-head screws 152 are inserted through holes 150 and are threaded into the tapped holes 148 to retain the cylindrical keys 144 in the grooves 142. The three screws 152 are tightened to only a moderate tightness so that the end 147 of each cylindrical key 144 can be flexed radially inwardly by a moderate force.

With the three keys 144 installed in the shaft 28, the collar 32 is slipped over the shaft 28, and the splined drive shaft 34 is inserted into the shaft 28 with three equiangular grooves in the splined drive shaft 34 receiving the three keys 144. The flat surface 146 on each key fits fiat against the flat bottom surface 34a of the associated longitudinal groove in the shaft 34 (FIG. 7). The collar 32 is radially drilled and tapped at three equiangular positions to provide three holes 158 for receiving slotted lock-screws 160 (FIGS. 6 and 8). The collar 32 is adjusted on the shaft 28 until the tapped holes are aligned with three radially drilled holes 162 in the shaft 28. The holes 162 are not threaded and each hole 162 extends into a semi-cylindrical groove 142. Thus when the coupling collar 32 is assembled, the three lock screws 160 are advanced into the drilled holes 162 in the shaft 28 where they engage the ends 147 of the three associated cylindrical keys 144. As the lock screws 160 are tightened, the ends 147 are flexed into tight engagement with the associated flat surface 34a in the splined shaft 34 and the shaft 34 is thereby coupled to the shaft 28. Even though the screws 152 are not tight they cannot become overloose or fall out because the collar 32 covers the heads of these screws, as seen in FIG. 7.

There are no loose keys which must be manipulated when coupling and uncoupling using this apparatus because the keys 144 are retained in the shaft 28 by the screws 152. To uncouple the shafts 34 and 28, the three lock screws 160 are merely loosened and the shaft 34 axially withdrawn. The shafts are coupled in the reverse manner.

It will be apparent that the coupling collar 32 can accommodate a large amount of variation in the spacing between the pump and a motor or engine having the drive shaft 34. The longitudinal hole in the shaft 28 is quite deep and permits the insertion of a splined drive shaft 34 to a depth which can vary in a range on the order of 3 or 4 inches. This coupling construction affords a great freedom in the spacing which can be achieved between a particular pump and motor or engine.

Variations and modifications of the disclosed pump and coupling structure will occur to those skilled in the art and these are intended to be covered by the claims which follow.

The invention having been thus described that which is new and desired to be protected by Letters Patent is:

1. A multiacylinder pump comprising a housing, means on said housing defining four pumping cylinders disposed in a circular formation at spaced diametrically opposed points on the periphery of the circle, a reciprocable piston in each of said cylinders, a piston rod attached to each of said pistons, a first rocking lever having the ends thereof engaged with two diametrically opposed piston rods, a second rocking lever having the ends thereof engaged with the other two diametrically opposed piston rods, a first and a second bearing member for separately rockably mounting said first and second levers respectively, a rotatable plate having a flat surface inclined with respect to the axis of plate rotation, said surface being disposed in engagement with the ends of each of said piston rods, and means for rotating said rotatable plate for reciprocating the piston rods and pistons successively in said pumping cylinders, retraction of one piston rod occurring in response to projection of the opposite piston rod under the control of the associated lever.

2. A multi-cylinder pump comprising a housing, means on said housing defining four pumping cylinders, said cylinders being arranged in pairs with the cylinders of each pair being disposed in diametrically opposed relationship and said cylinders having parallel longitudinal axes, a reciprocable piston in each of said cylinders, a piston rod attached to each of said pistons, a first rocking lever having the ends thereof engaged with two diametrically opposed piston rods, a second rocking lever having the ends thereof engaged with the other two diametrically opposed piston rods, a rotatable plate having a fiat surface inclined with respect to the axis of plate rotation, said surface being disposed in engagement with the ends of each of said piston rods, a first and a second spring means engaged with said first and said second rocking levers respectively for urging said levers to maintain the engagement of the ends of the two piston rods associated therewith and the incined surface of said plate, and means for rotating said rotatable plate for reciprocating the piston rods and pistons successively in said pumping cylinder-s, retraction of one piston rod occurring in response to projection of the opposite piston rod under the control of the associated lever.

3. A multi-cylinder pump comprising a housing, said housing having a longitudinal axis, means on said housing defining four pumping cylinders, said cylinders being arranged in pairs with the cylinders of each pair being disposed in diametrically opposed relationship around said housing axis, a reciprocable piston in each of said cylinders, a piston rod attached to each of said pistons, a first rocking lever having the ends thereof engaged with two diametrically opposed piston rods, a second rocking lever having the ends thereof engaged with the other two diametrically opposed piston rods, universally pivotable shoes located at the ends of each of said piston rods each of said shoes having a flat surface thereon, a rotatable plate having a flat surface inclined with respect to the axis of plate rotation said flat plate surface disposed in engagement with the flat surfaces of the shoes, a first and a second bearing member for separately mounting said first and second levers respectively, spring means engaged with each of said bearing members for urging said levers to maintain the engagement of said flat surfaces, and means for rotating said rotatable plate for reciprocating the four piston rods successively in their respective pumping cylinders, retraction of one piston rod occurring in response to projection of the opposite piston rod under the control of the associated lever.

4. A multi-lcylinder pump having a longitudinal axis comprising a housing, means on said housing defining four longitudinally extending pumping cylinders arranged in pairs with the cylinders of each pair being disposed in diametrically opposed relationship, a reciprocating piston in each of said cylinders, a piston rod attached to each of said pistons, a first rocking lever having the ends thereof engaged with two opposed piston rods, a second rocking lever having the ends thereof engaged with the other two opposed piston rods, universally pivotable shoes located at the ends of each of said piston rods each of said shoes having a flat surface thereon, a rotatable plate having a flat surface inclined with respect to the axis of plate rotation said flat plate surface disposed in engagement with the fiat surfaces of the shoes, a first force applying member having an axial hole therethrough and having a bearing surface on one end thereof engaging said first rocking lever, a first spring \for urging said first force applying member and said first lever to maintain the engagement of said flat surfaces, a second force applying member said second member being slidably received in References Cited in the file of this patent UNITED STATES PATENTS Brown Aug. 3, Sappington Sept. 23, Webb Mar. 4, Cervo Dec. 29, Norlin Mar. 29,

FOREIGN PATENTS Germany Apr. 25, 

